Pancreatic polypeptide response to oral glucose load in patients with liver cirrhosis--interrelationship between PP and other pancreatic endocrine hormones

The purpose of the present study was to elucidate the interrelationship between pancreatic polypeptide (PP) and other pancreatic endocrine hormones. For this purpose, a radioimmunoassay (RIA) system of plasma PP was established and the changes in plasma PP, plasma immunoreactive insulin (IRI), plasma C-peptide reactivity (CPR) and plasma immunoreactive glucagon (IRG) following oral administration of glucose were examined in ten normal subjects and twenty-five patients with liver cirrhosis. Patients with liver cirrhosis were classified into a normal glucose tolerance group (NGT), an impaired glucose tolerance group (IGT), and a diabetes mellitus group (DM) on the basis of the glucose tolerance curves obtained after the oral administration of glucose. In the IGT and DM groups, fasting plasma PP levels were significantly elevated when compared with those in the control and NGT groups. Also oral administration of 75g glucose elicited an exaggerated rise in plasma PP in the IGT and DM groups when compared with the response in the control and NGT groups. On the other hand, PP response to glucose in the NGT group was similar to that in the control group. Plasma IRI increased markedly before and after oral administration of glucose in the IGT and DM groups when compared with the control groups. In these patients, plasma levels of CPR almost paralleled those of IRI. No significant difference was noted between the NGT group and the control group with regard to plasma IRI and CPR levels before and after oral glucose loading. Accordingly, insufficient insulin action was considered to exist in the IGT and DM groups. This insufficiency in insulin action was expressed in terms of the indices of increase in plasma IRI and CPR, delta IRI/delta BS and delta CPR/delta BS, which corresponded to the elevated blood glucose levels, being significantly lower in the IGT and DM groups than in the control and NGT groups 30 minutes after oral administration of glucose. No significant difference was noticeable between the NGT group and control group with regard to these indices. In the patients with liver cirrhosis, the delta PP value, obtained by subtracting the plasma PP level during fasting from the PP level 30 minutes after oral glucose loading, was inversely correlated with the values of both delta IRI/delta BS and delta CPR/delta BS.(ABSTRACT TRUNCATED AT 400 WORDS)